Can't select 2.4 channel on N66U

When I try to set anything other than AUTO for 2.4 wireless it changes back to 20/40 and AUTO.
I can change from 20/40 to 20 and save. But as soon as I change the channel is resets.
And the channel selected by AUTO is very crowded so I need to set channel manually.
Happens on the two latest builds (trid updating just now)